CN107992974B - Optimization method of vacuum heat treatment distribution matrix - Google Patents
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Abstract
The invention discloses an optimization method of a vacuum heat treatment material distribution matrix, relates to the technical field of vacuum heat treatment furnaces, and solves the technical problem that research on rules of influence of the material distribution matrix on heating efficiency and temperature field uniformity is less. The optimization method of the vacuum heat treatment material distribution matrix respectively simulates vacuum heating of a round bar under different material distribution matrixes of a forward row type and a cross row type and a round plate under different material distribution matrixes of a vertical row type and a transverse row type, the temperature is raised to 650 ℃ at a heating rate of 15 ℃/min, the temperature is kept for 60min, the temperature is raised to 950 ℃ at a heating rate of 12 ℃/min, the temperature is kept for 30min, and a free tetrahedron unit is selected for mesh subdivision; assuming that the initial temperatures of the heating chamber, the graphite tube heater and the workpiece are constant and are all 25 ℃, only radiation heat exchange exists on the surface of an object in the heating chamber, thin gas is taken as a transparent medium, convection heat exchange is not considered, and the influence of a material frame and a material frame base on the temperature field of the heating chamber is not considered.
Description
Technical Field
The invention relates to the technical field of vacuum heat treatment furnaces, in particular to an optimization method of a vacuum heat treatment material distribution matrix.
Background
The heat radiation is an electromagnetic wave which is transmitted along a straight line, and different workpieces can be mutually shielded, so that a surface which cannot be directly incident to the heat radiation is formed, the surface is called a radiation dark area, the radiation dark area can directly influence the heating efficiency and the uniformity of the temperature field of an effective heating area, and the size of the radiation dark area is determined by a cloth matrix.
At present, workpieces processed by vacuum heat treatment equipment mainly comprise shafts, nozzles, gears, bearings and the like, and the shapes of the workpieces can be roughly classified into two types: a long cylinder and a short cylinder. The invention carries out vacuum heat treatment heating process simulation by using circular bars and circular plates to represent typical vacuum heat treatment parts, and researches the influence rule of a distribution matrix on heating efficiency and temperature field uniformity.
Therefore, how to provide an optimization method of a vacuum heat treatment material distribution matrix to provide theoretical guidance for workpiece arrangement in the actual production process becomes a technical problem to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide an optimization method of a vacuum heat treatment material distribution matrix, which aims to solve the technical problems that the research on the rule of the material distribution matrix influencing heating efficiency and temperature field uniformity is less, and theoretical guidance cannot be provided for workpiece arrangement in the actual production process.
The invention provides an optimization method of a material distribution matrix for vacuum heat treatment, which simulates 16 phi 40mm multiplied by 200mm specification 20CrMnTi round bars, and respectively carries out vacuum heating under two different material distribution matrixes of a row type and a fork row type, and the specific heating process comprises the following steps: heating to 650 deg.C at a heating rate of 15 deg.C/min, maintaining for 60min, heating to 950 deg.C at a heating rate of 12 deg.C/min, and maintaining for 30 min; selecting free tetrahedral units for mesh subdivision, wherein the number of the arranged tetrahedral units is 22000, the lowest unit mass is 0.19, and the average unit mass is 0.56; the number of the staggered tetrahedral units is 43830, the minimum unit mass is 0.27, and the average unit mass is 0.56; the numerical model makes the following assumptions: assuming that the initial temperatures of the heating chamber, the graphite tube heater and the workpiece are constant, and are all 25 ℃; assuming that only radiation heat transfer exists on the surface of an object in the heating chamber, thin gas is taken as a transparent medium, and convection heat transfer is not considered; the influence of the material frame and the material frame base on the temperature field of the heating chamber is not considered.
Wherein, the sequential arrangement type has symmetry, and an 1/2 model is adopted for numerical simulation; the fork-row type does not have symmetry, and numerical simulation is carried out by adopting a complete model.
Specifically, under two different cloth matrix forms of a row-by-row type and a fork-row type, the heating rates of the row-by-row type edge workpiece and the center workpiece are higher than those of the fork-row type edge workpiece and the center workpiece, and the heating rate difference of the center workpiece is larger.
Furthermore, the heating hysteresis phenomenon of the central workpiece is more obvious under the condition of cross-row type material distribution, and the difference from the furnace temperature is larger; keeping the temperature in the preheating section for 60min, wherein the difference between the sequential type core part workpiece and the furnace temperature is 9 ℃, and the difference between the fork type core part workpiece and the furnace temperature is 13 ℃; and (3) preserving the temperature for 30min after the furnace temperature reaches the set temperature of 950 ℃, wherein the difference between the front-row type core workpiece and the furnace temperature is 5 ℃, and the difference between the fork-row type core workpiece and the furnace temperature is 10 ℃.
Furthermore, the maximum temperature difference of the in-line type temperature field is 135 ℃, and the maximum temperature difference of the cross-row type temperature field is 144 ℃; the adoption of the row-type material distribution has more uniform temperature distribution and faster heating rate, the temperature difference between the edge part workpiece and the core part workpiece of the fork-row type material distribution is larger, and the condition of local overheating occurs.
Compared with the prior art, the optimization method of the vacuum heat treatment material distribution matrix has the following advantages:
according to the optimization method of the material distribution matrix for vacuum heat treatment, provided by the invention, under the same heating process condition, the temperature rise curve and the temperature distribution cloud chart of the round bar under the conditions of the two material distribution matrixes of the row type and the fork type are compared, the row type material distribution is adopted, the temperature rise rate of the workpiece is higher than that of the fork type, the temperature distribution of an effective heating area is more uniform, and the arrangement of the workpiece is more compact, so that the row type material distribution matrix is preferably selected when the long-axis part is subjected to vacuum heating.
The invention also provides an optimization method of the vacuum heat treatment material distribution matrix, which simulates 48 circular plates of 20CrMnTi with the specification of phi 120mm multiplied by 15mm, and respectively carries out vacuum heating under two different material distribution matrixes of a vertical type and a horizontal type, wherein the specific heating process is as follows: heating to 650 deg.C at a heating rate of 15 deg.C/min, maintaining for 60min, heating to 950 deg.C at a heating rate of 12 deg.C/min, and maintaining for 30 min; selecting free tetrahedral units to perform mesh subdivision, wherein the number of the horizontal tetrahedral units is 24951, the lowest unit mass is 0.26, and the average unit mass is 0.52; the number of vertical tetrahedral units is 24918, the lowest unit mass is 0.26, and the average unit mass is 0.52; the numerical model makes the following assumptions: assuming that the initial temperatures of the heating chamber, the graphite tube heater and the workpiece are constant, and are all 25 ℃; assuming that only radiation heat transfer exists on the surface of an object in the heating chamber, thin gas is taken as a transparent medium, and convection heat transfer is not considered; the influence of the material frame and the material frame base on the temperature field of the heating chamber is not considered.
The vertical arrangement is that the direction of the central axis of the workpiece is parallel to the direction of the central axis of the graphite tube, and the horizontal arrangement is that the direction of the central axis of the workpiece is parallel to the direction of the central axis of the graphite tube.
Specifically, the circular plate is in a horizontal distribution matrix form and a vertical distribution matrix form, the horizontal heating rate of the edge workpieces is greater than that of the vertical distribution workpieces, and the vertical distribution heating rate of the center workpieces is greater than that of the horizontal workpieces.
Furthermore, a transverse-row type material distribution matrix is adopted, the difference between the core part workpiece and the furnace temperature is larger, and the heating hysteresis phenomenon is more obvious; the maximum temperature difference of the core table of the horizontal type core workpiece is 68 ℃ and is 60 ℃ higher than that of the core table of the vertical type core workpiece.
Furthermore, the maximum temperature difference of the horizontal temperature field is 238 ℃, the maximum temperature difference of the vertical temperature field is 175 ℃, and the minimum temperature of the vertical temperature field is higher than that of the horizontal temperature field; by adopting the vertical distribution matrix, the temperature field distribution in the heating process is more uniform, and the heating rate of the central workpiece is higher.
Compared with the prior art, the optimization method of the vacuum heat treatment material distribution matrix has the following advantages:
according to the optimization method of the material distribution matrix for vacuum heat treatment, provided by the invention, under the same heating process condition, the temperature rise curve and the temperature distribution cloud chart of a circular plate under the conditions of a horizontal type material distribution matrix and a vertical type material distribution matrix are compared, so that the temperature rise speed of a central workpiece is higher and the temperature distribution of an effective heating area is more uniform by adopting vertical type material distribution, and therefore, when a plate part is subjected to vacuum heating, the vertical type material distribution matrix is preferably selected.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a schematic diagram of a row-by-row distribution structure of round bars in an optimization method of a vacuum heat treatment distribution matrix according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a row-by-row distribution structure of round bars in the optimization method of a vacuum heat treatment distribution matrix according to an embodiment of the present invention;
fig. 3 is a schematic diagram of an arrangement structure of round bars in an staggered manner in the optimization method of a vacuum heat treatment material distribution matrix according to an embodiment of the present invention;
fig. 4 is a schematic diagram of an arrangement structure of round bars in an staggered manner in the optimization method of a vacuum heat treatment material distribution matrix according to an embodiment of the present invention;
fig. 5 is a schematic diagram of mesh generation of round bars in a row in the optimization method of a vacuum heat treatment material distribution matrix according to the embodiment of the present invention;
fig. 6 is a schematic cross-bar grid division diagram of a circular bar in the optimization method of a vacuum heat treatment material distribution matrix according to the embodiment of the present invention;
fig. 7 is a schematic view of a temperature rise curve of a circular bar under different material distribution matrixes in the optimization method of the material distribution matrix for vacuum heat treatment according to the embodiment of the present invention;
fig. 8 is a schematic diagram of a temperature difference curve of a circular bar under different material distribution matrixes in the optimization method of the material distribution matrix for vacuum heat treatment according to the embodiment of the invention;
fig. 9 is a schematic diagram of a horizontal distribution structure of circular plates in the optimization method of a vacuum heat treatment distribution matrix according to the embodiment of the present invention;
fig. 10 is a schematic diagram illustrating a horizontal distribution structure of circular plates in the method for optimizing a vacuum heat treatment distribution matrix according to the embodiment of the present invention;
fig. 11 is a schematic view of a vertical distribution structure of circular plates in the optimization method of a distribution matrix for vacuum heat treatment according to the embodiment of the present invention;
fig. 12 is a schematic view of a vertical distribution structure of circular plates in the optimization method of a distribution matrix for vacuum heat treatment according to the embodiment of the present invention;
fig. 13 is a schematic diagram of mesh subdivision of a horizontal row of circular plates in the optimization method of a vacuum heat treatment material distribution matrix according to the embodiment of the present invention;
fig. 14 is a schematic diagram of vertical grid division of a circular plate in the optimization method of a vacuum heat treatment material distribution matrix according to the embodiment of the present invention;
fig. 15 is a schematic view of a temperature rise curve of a workpiece on the lower edge portions of different material distribution matrices of a circular plate in the optimization method for a material distribution matrix for vacuum heat treatment according to the embodiment of the present invention;
fig. 16 is a schematic view of a temperature rise curve of a workpiece in the lower center part of different material distribution matrices of a circular plate in the optimization method of the material distribution matrix for vacuum heat treatment according to the embodiment of the present invention;
fig. 17 is a schematic diagram of a temperature difference curve between the furnace temperature and the workpiece core of the circular plate in the optimization method of the vacuum heat treatment material distribution matrix according to the embodiment of the present invention under different material distribution matrices;
fig. 18 is a schematic diagram of a temperature difference curve of a workpiece core surface of a circular plate under different material distribution matrixes in the optimization method of the material distribution matrix for vacuum heat treatment according to the embodiment of the present invention.
In the figure: 1-edge workpiece; 2-core part of the workpiece; s-surface temperature; c-center temperature.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; the connection can be mechanical connection or electrical connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Fig. 1 is a schematic diagram of a row-by-row distribution structure of round bars in an optimization method of a vacuum heat treatment distribution matrix according to an embodiment of the present invention; fig. 2 is a schematic diagram of a row-by-row distribution structure of round bars in the optimization method of a vacuum heat treatment distribution matrix according to an embodiment of the present invention; fig. 3 is a schematic diagram of an arrangement structure of round bars in an staggered manner in the optimization method of a vacuum heat treatment material distribution matrix according to an embodiment of the present invention; fig. 4 is a schematic diagram of an arrangement structure of round bars in an staggered manner in the optimization method of a vacuum heat treatment material distribution matrix according to an embodiment of the present invention; fig. 5 is a schematic diagram of mesh generation of round bars in a row in the optimization method of a vacuum heat treatment material distribution matrix according to the embodiment of the present invention; fig. 6 is a schematic cross-row grid division diagram of a circular bar in the optimization method of the distribution matrix for vacuum heat treatment according to the embodiment of the present invention.
The embodiment of the invention provides an optimization method of a vacuum heat treatment material distribution matrix, as shown in figures 1-4 and combined with figures 5 and 6, 16 round bars of 20CrMnTi with the specification of phi 40mm multiplied by 200mm are simulated, vacuum heating is respectively carried out under two different material distribution matrixes of a parallel type and a staggered type, and the specific heating process comprises the following steps: heating to 650 deg.C at a heating rate of 15 deg.C/min, maintaining for 60min, heating to 950 deg.C at a heating rate of 12 deg.C/min, and maintaining for 30 min; selecting free tetrahedral units for mesh subdivision, wherein the number of the arranged tetrahedral units is 22000, the lowest unit mass is 0.19, and the average unit mass is 0.56; the number of the staggered tetrahedral units is 43830, the minimum unit mass is 0.27, and the average unit mass is 0.56; the numerical model makes the following assumptions: assuming that the initial temperatures of the heating chamber, the graphite tube heater and the workpiece are constant, and are all 25 ℃; assuming that only radiation heat transfer exists on the surface of an object in the heating chamber, thin gas is taken as a transparent medium, and convection heat transfer is not considered; the influence of the material frame and the material frame base on the temperature field of the heating chamber is not considered.
Compared with the prior art, the optimization method of the vacuum heat treatment material distribution matrix has the following advantages:
according to the optimization method of the material distribution matrix for vacuum heat treatment provided by the embodiment of the invention, under the same heating process condition, the temperature rise curve and the temperature distribution cloud chart of the round bar under the condition of two material distribution matrixes of a row type and a fork type are compared, the row type material distribution is adopted, the temperature rise rate of a workpiece is higher than that of the fork type, the temperature distribution of an effective heating area is more uniform, and the arrangement of the workpiece is more compact, so that the row type material distribution matrix is preferably selected when the long-axis part is subjected to vacuum heating.
As shown in fig. 1, 2 and 5, the in-line mode has symmetry, and an 1/2 model can be adopted for numerical simulation; as shown in fig. 3, 4 and 6, the cross-row type has no symmetry, and numerical simulation can be performed by using a complete model.
Fig. 7 is a schematic view of a temperature rise curve of a circular bar under different material distribution matrixes in the optimization method for vacuum heat treatment of the material distribution matrix according to the embodiment of the invention.
Specifically, as shown in fig. 7, in two different material distribution matrix forms of the row-wise type and the fork-wise type, the heating rates of the row-wise type edge workpiece 1 and the center workpiece 2 are both higher than the fork-wise type, and the difference between the heating rates of the center workpiece 2 is larger. Because the heat of the workpiece is from the heat radiation of the graphite electrode, and the shielding of the workpiece 2 at the center of the staggered cloth matrix is more serious, the absorbed heat radiation is less, and the heating rate is slow.
Fig. 8 is a schematic diagram of a temperature difference curve of a circular bar under different material distribution matrixes in the optimization method of the material distribution matrix for vacuum heat treatment according to the embodiment of the invention.
Further, as shown in fig. 8, the heating hysteresis of the central workpiece 2 is more obvious under the cross-row type material distribution condition, and the difference from the furnace temperature is larger; keeping the temperature of the preheating section for 60min, wherein the difference between the front-row type core part workpiece 2 and the furnace temperature is 9 ℃, and the difference between the fork-row type core part workpiece 2 and the furnace temperature is 13 ℃; and (3) preserving the temperature for 30min after the furnace temperature reaches the set temperature of 950 ℃, wherein the difference between the front-row type core part workpiece 2 and the furnace temperature is 5 ℃, and the difference between the fork-row type core part workpiece 2 and the furnace temperature is 10 ℃.
Furthermore, the maximum temperature difference of the in-line type temperature field is 135 ℃, and the maximum temperature difference of the cross-row type temperature field is 144 ℃; the adoption of the row-type material distribution has more uniform temperature distribution and faster heating rate, the temperature difference between the edge part workpiece 1 and the core part workpiece 2 of the fork-type material distribution is larger, and the situation of local overheating occurs. Because the straight-row type center part workpiece 2 and the edge part workpiece 1 are respectively positioned at the vertex and the center of a square, and the cross-row type center part workpiece 2 and the edge part workpiece 1 are respectively positioned at the vertex and the center of a diamond, the distance between the two workpieces is farther, the radiation angle coefficient of the edge part workpiece 1 to the center part workpiece 2 is smaller, and the radiation energy of the edge part workpiece 1 incident to the center part workpiece 2 is reduced; in addition, the in-line type workpieces are shielded by only 4 workpieces on a circumference which is 70mm away from the central axis of the in-line type workpieces, and the cross-line type workpieces are shielded by 6 workpieces on the same circumference, so that shielding is more serious.
In conclusion, when the long-axis parts are subjected to vacuum heating, the sequential arrangement type distribution matrix is selected, so that the heating rate is higher, the temperature uniformity is better, and the space is saved.
Fig. 9 is a schematic diagram of a horizontal distribution structure of circular plates in the optimization method of a vacuum heat treatment distribution matrix according to the embodiment of the present invention; fig. 10 is a schematic diagram illustrating a horizontal distribution structure of circular plates in the method for optimizing a vacuum heat treatment distribution matrix according to the embodiment of the present invention; fig. 11 is a schematic view of a vertical distribution structure of circular plates in the optimization method of a distribution matrix for vacuum heat treatment according to the embodiment of the present invention; fig. 12 is a schematic view of a vertical distribution structure of circular plates in the optimization method of a distribution matrix for vacuum heat treatment according to the embodiment of the present invention; fig. 13 is a schematic diagram of mesh subdivision of a horizontal row of circular plates in the optimization method of a vacuum heat treatment material distribution matrix according to the embodiment of the present invention; fig. 14 is a schematic diagram of vertical grid division of a circular plate in the optimization method of a vacuum heat treatment material distribution matrix according to the embodiment of the present invention.
The embodiment of the invention also provides an optimization method of the material distribution matrix by vacuum heat treatment, as shown in fig. 9-12 combined with fig. 13 and 14, 48 pieces of 20CrMnTi round plate materials with the specification of phi 120mm multiplied by 15mm are simulated, vacuum heating is respectively carried out under two different material distribution matrixes of a vertical type and a horizontal type, and the specific heating process is as follows: heating to 650 deg.C at a heating rate of 15 deg.C/min, maintaining for 60min, heating to 950 deg.C at a heating rate of 12 deg.C/min, and maintaining for 30 min; selecting free tetrahedral units to perform mesh subdivision, wherein the number of the horizontal tetrahedral units is 24951, the lowest unit mass is 0.26, and the average unit mass is 0.52; the number of vertical tetrahedral units is 24918, the lowest unit mass is 0.26, and the average unit mass is 0.52; the numerical model makes the following assumptions: assuming that the initial temperatures of the heating chamber, the graphite tube heater and the workpiece are constant, and are all 25 ℃; assuming that only radiation heat transfer exists on the surface of an object in the heating chamber, thin gas is taken as a transparent medium, and convection heat transfer is not considered; the influence of the material frame and the material frame base on the temperature field of the heating chamber is not considered.
Compared with the prior art, the optimization method of the vacuum heat treatment material distribution matrix has the following advantages:
in the optimization method of the material distribution matrix for vacuum heat treatment provided by the embodiment of the invention, under the same heating process condition, the temperature rise curve and the temperature distribution cloud chart of the circular plate under the conditions of the two material distribution matrixes of the horizontal type and the vertical type are compared, so that the temperature rise speed of the central workpiece is higher and the temperature distribution of an effective heating area is more uniform by adopting the vertical type material distribution, and therefore, when the plate part is subjected to vacuum heating, the vertical type material distribution matrix is preferably selected.
As shown in fig. 11, 12 and 14, the vertical arrangement is that the central axis direction of the workpiece is parallel to the central axis direction of the graphite tube; as shown in fig. 9, 10 and 13, the workpiece center axis and the graphite tube center axis are parallel to each other in the horizontal row. Furthermore, because the geometric model has symmetry, one-half of the model can be used for simulation.
Fig. 15 is a schematic view of a temperature rise curve of a workpiece on the lower edge portions of different material distribution matrices of a circular plate in the optimization method for a material distribution matrix for vacuum heat treatment according to the embodiment of the present invention; fig. 16 is a schematic view of a temperature rise curve of a workpiece in the lower center part of different material distribution matrixes in a circular plate in the optimization method of the material distribution matrix for vacuum heat treatment according to the embodiment of the present invention.
Specifically, as shown in fig. 15 and 16, when the circular plate is in a horizontal type and a vertical type different material distribution matrix form, the temperature rise rate of the side workpiece 1 in the horizontal type is greater than that in the vertical type, and the temperature rise rate of the center workpiece 2 in the vertical type material distribution is greater than that in the horizontal type. Because the end face of the edge part workpiece 1 can receive the heat radiation of the whole length direction of the graphite tube under the horizontal distribution matrix, and only the heat radiation of the graphite tube with partial length can be incident to the end face of the edge part workpiece 1 under the vertical distribution matrix; for the central workpiece 2, the temperature is raised mainly by the heat radiation absorbed by the side surface, and obviously, the shielding of the side surface of the horizontal type central workpiece 2 is more serious.
Fig. 17 is a schematic diagram of a temperature difference curve between the furnace temperature and the workpiece core of the circular plate in the optimization method of the vacuum heat treatment material distribution matrix according to the embodiment of the present invention under different material distribution matrices; fig. 18 is a schematic diagram of a temperature difference curve of a workpiece core surface of a circular plate under different material distribution matrixes in the optimization method of the material distribution matrix for vacuum heat treatment according to the embodiment of the present invention.
Further, as shown in fig. 17 and 18, by using the horizontal distribution matrix, the difference between the core workpiece 2 and the furnace temperature is larger, and the heating hysteresis is more obvious; the maximum temperature difference of the core surface of the horizontal type core workpiece 2 is 68 ℃ and is 60 ℃ higher than that of the core surface of the vertical type core workpiece 2. In the horizontal distribution matrix, the shading of the shadow side of the central workpiece 2 is tighter than that of the vertical distribution matrix, so that the heating rate of the central temperature C of the central workpiece 2 is greatly lower than the surface temperature S.
Furthermore, the maximum temperature difference of the horizontal temperature field is 238 ℃, the maximum temperature difference of the vertical temperature field is 175 ℃, and the minimum temperature of the vertical temperature field is higher than that of the horizontal temperature field; by adopting the vertical distribution matrix, the temperature field distribution in the heating process is more uniform, and the heating rate of the core part workpiece 2 is higher. Because the heating time is determined by the point with the slowest temperature rise rate in the whole effective heating area, the vertical cloth heating efficiency is higher.
In conclusion, when the plate type parts are subjected to vacuum heating, the vertical distribution matrix is selected, so that the heating rate is higher, and the temperature uniformity is better.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (6)
1. The optimization method of the vacuum heat treatment material distribution matrix is characterized in that 16 20CrMnTi round bars with the specification of phi 40mm multiplied by 200mm are simulated and are respectively heated in vacuum under two different material distribution matrixes of a row type and a fork row type, and the specific heating process comprises the following steps: heating to 650 deg.C at a heating rate of 15 deg.C/min, maintaining for 60min, heating to 950 deg.C at a heating rate of 12 deg.C/min, and maintaining for 30 min;
the heating rates of the edge workpieces and the center workpieces of the parallel arrangement type are higher than those of the fork arrangement type under two different material distribution matrix forms of the parallel arrangement type and the fork arrangement type of the round bars, and the heating rate difference of the center workpieces is larger;
the maximum temperature difference of the forward-arranged temperature field is 135 ℃, and the maximum temperature difference of the cross-arranged temperature field is 144 ℃; the adoption of the row-type material distribution has more uniform temperature distribution and faster heating rate, the temperature difference between the edge part workpiece and the core part workpiece of the fork-row type material distribution is larger, and the condition of local overheating occurs.
2. The method for optimizing a vacuum heat treatment distribution matrix according to claim 1, wherein the in-line type has symmetry, and numerical simulation is performed by adopting an 1/2 model; the fork-row type does not have symmetry, and numerical simulation is carried out by adopting a complete model.
3. The optimization method of the vacuum heat treatment material distribution matrix according to claim 1, wherein the heating hysteresis of the central workpiece is more obvious under the cross-bar type material distribution condition, and the difference between the heating hysteresis and the furnace temperature is larger;
keeping the temperature in the preheating section for 60min, wherein the difference between the sequential type core part workpiece and the furnace temperature is 9 ℃, and the difference between the fork type core part workpiece and the furnace temperature is 13 ℃; and (3) preserving the temperature for 30min after the furnace temperature reaches the set temperature of 950 ℃, wherein the difference between the front-row type core workpiece and the furnace temperature is 5 ℃, and the difference between the fork-row type core workpiece and the furnace temperature is 10 ℃.
4. An optimization method of a vacuum heat treatment material distribution matrix is characterized in that 48 pieces of 20CrMnTi round plate materials with the specification of phi 120mm multiplied by 15mm are simulated and are respectively heated in vacuum under two different material distribution matrixes of a vertical type and a horizontal type, and the specific heating process is as follows: heating to 650 deg.C at a heating rate of 15 deg.C/min, maintaining for 60min, heating to 950 deg.C at a heating rate of 12 deg.C/min, and maintaining for 30 min;
the circular plate is in a horizontal distribution matrix form and a vertical distribution matrix form, the horizontal heating rate of the edge workpieces is greater than that of the vertical workpieces, and the vertical distribution heating rate of the center workpieces is greater than that of the horizontal workpieces;
the horizontal distribution matrix is adopted, the difference between the core workpiece and the furnace temperature is larger, and the heating hysteresis phenomenon is more obvious; the maximum temperature difference of the core table of the horizontal type core workpiece is 68 ℃ and is 60 ℃ higher than that of the core table of the vertical type core workpiece.
5. The optimization method of the vacuum heat treatment material distribution matrix according to claim 4, wherein the vertical arrangement is that the central axis direction of the workpiece is parallel to the central axis direction of the graphite tube, and the horizontal arrangement is that the central axis direction of the workpiece is parallel to the central axis direction of the graphite tube.
6. The optimization method of the vacuum heat treatment material distribution matrix according to claim 4 or 5, wherein the maximum temperature difference of the horizontal temperature field is 238 ℃, the maximum temperature difference of the vertical temperature field is 175 ℃, and the minimum temperature of the vertical temperature field is higher than that of the horizontal temperature field; by adopting the vertical distribution matrix, the temperature field distribution in the heating process is more uniform, and the heating rate of the central workpiece is higher.
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